Helpful hints for the successful treatment of canine atopy

We're at the height of allergy season here in the Midwest after enduring an extremely high tree pollen and grass pollen season. Needless to say, people with atopy have been suffering along with our pets. Even if you're not allergic, the high pollen counts tend to act as an irritant, bothering both mucous membranes and the respiratory system.

The conventional means of controlling the clinical signs of canine atopy have been discussed in the past (see http://dvm360.com/dermatology). Here I want to offer some small pearls based on new evidence of the pathogenesis of atopy that may make your patients more comfortable.

Topical measures

Photo 1. Clinical signs of atopy can include alopecia and excoriation as seen in this young dog from rubbing its face. (PHOTOS COURTESY OF DR. ALICE JEROMIN)

Topicals such as shampoos, leave-on anti-itch conditioners and ceramide replacement products seem to have gained new importance based on the pathogenesis of atopy in dogs. New evidence shows that absorption of the allergen across the skin (percutaneous absorption) may be the primary mode of getting the allergic response started.1,2 It certainly explains why in dogs with atopy, the face, feet and perineal areas are most often involved (Photos 1 and 2).

Photo 2. A common sign of atopy in dogs is licking of the caudal carpus, as evidenced by the alopecia and the copper-colored staining of the adjacent fur from saliva.

Once sensitized, dendritic cells that "patrol" the body are presented with antigen, which starts the immune system going, switching to T-helper lymphocyte-2 production with consequent cytokines that create inflammation. Ceramide production/destruction, filaggrin, and other structural elements of the epidermis are compromised, resulting in destruction of the normal skin barrier.1,2 This results in more absorption of the allergen across the skin. Also, the normal resident bacteria of the skin tends to multiply and produces enzymes that further break down ceramide.1,2

After a while, chronic changes occur that are difficult to reverse and further perpetuate the condition. Frequent bathing helps to remove the allergen, which can prevent the whole process from starting. It also reduces bacterial colonization. Since frequent bathing can be helpful in most dogs, choose a shampoo that is mild without ingredients that may cause drying (dry skin enhances allergy absorption). A hypoallergenic shampoo followed by a topical low-potency, water-based hydrocortisone such as Resicort (Virbac Animal Health) as a leave-on rinse can help "put the fire out." Shampoos with phytosphingosines can be helpful in keeping the epidermal barrier in check.

Wiping off the feet, ventral abdomen, medial pinna and perineal areas (the nonhaired areas of the body) when dogs come in from outside will reduce the pollen load. Using just a damp cloth or antibacterial wipes such as Preva Medicated Wipes (Bayer Animal Health) or the bovine nisin wipes (Wipe Out Dairy Wipes—ImmuCell) is inexpensive and helpful. Clothing such as cotton t-shirts and onesies can act as a barrier to percutaneous absorption of allergens.

Topical skin lipid complexes containing ceramides, botanicals and fatty acids such as Allerderm Spot-on (Virbac Animal Health) and Dermoscent Essential 6 (Aventix) can help repair stratum corneum lipids.3 This can aid in restoring a normal skin barrier. The topicals are typically used once weekly but can be used more or less often depending on the patient's response.